This paper presents the generation and the verification of the few-group homogenized cross section for Batan-FUEL code. This code is routinely used for fuel management in the G. A. Siwabessy Multipurpose Reactor (RSG-GAS). The Monte Carlo code Serpent 2 code, in conjunction with the latest nuclear data library ENDF/B-VIII.0, was used. Calculations using the existing newly generated few-group cross section data were carried out for the 88th core. The calculated core parameters such as excess reactivity and control rod worth are compared to the available experimental data. On the other hand, the fuel burnup fraction and radial power peaking factor (PPF) are compared to the results of Serpent 2. It was shown that the new cross section data have more consistency and a better agreement excess reactivity and control rod worth compared to the experimental data. Similarly, the U-235 burnup fraction and radial power peaking factor by the new cross section data are also shown to concur well with Serpent 2. The newly generated few-group cross section is recommended to replace the existing ones for the fuel management of RSG-GAS.